%0 Journal Article
%T A new photoionization-induced substitution reaction chemical ionization time-of-flight mass spectrometry for highly sensitive detection of trace exhaled ethylene.
%A Zhang B
%A Hua L
%A Fan Z
%A Wen Y
%A Zhang L
%A Xie Y
%A Gao Y
%A Jiang J
%A Li H
%J Anal Chim Acta
%V 1317
%N 0
%D 2024 Aug 15
%M 39030010
%F 6.911
%R 10.1016/j.aca.2024.342910
%X Highly sensitive and rapid detection of ethylene, the smallest alkene of great significance in human physiological metabolism remains a great challenge. In this study, we developed a new photoionization-induced substitution reaction chemical ionization time-of-flight mass spectrometry (PSCI-TOFMS) for trace exhaled ethylene detection. An intriguing ionization phenomenon involving a substitution reaction between the CH2Br2+ reactant ion and ethylene molecule was discovered and studied for the first time. The formation of readily identifiable [CH2Br·C2H4]+ product ion greatly enhanced the ionization efficiency of ethylene, which led to approximately 800-fold improvement of signal intensity over that in single photon ionization mode. The CH2Br2+ reactant ion intensity and ion-molecule reaction time were optimized, and a Nafion tube was employed to eliminate the influence of humidity on the ionization of ethylene. Consequently, a limit of detection (LOD) as low as 0.1 ppbv for ethylene was attained within 30 s at 100 % relative humidity. The application of PSCI-TOFMS on the rapid detection of trace amounts of exhaled ethylene from healthy smoker and non-smoker volunteers demonstrated the satisfactory performance and potential of this system for trace ethylene measurement in clinical diagnosis, atmospheric measurement, and process monitoring.